Interactions between mammalian sensory nerves and oral epithelium will be studied during differentiation of lingual taste buds and gustatory papillae in fetal sheep. This examination of fetal nerve-epithelial interactions will provide a basis for understanding neurotrophic influences during oral-faciAl development. The inductive influence of non-taste nerves on lingual epithelium will be studied, as will the influence of taste nerves on non-lingual epithelium. Using sterile surgical procedures in fetal sheep early in gestation, cross-grafts will be made between dorsal tongue mucosa and other types of orofacial epithelia. Near the end of gestation, grafts will be dissected and microsopically examined for the presence of taste buds, taste papillae, and nerves. To determine whether taste buds that may form in grafted epithelial tissues are functional, electrophysiological recordings will be made from the innervation to grafted tissues; grafts will be stimulated with chemicals and tactile stimuli. The experiments will increase knowledge of: inductive and neurotrophic influences in the oral cavity during development: tissue healing and epithelial graft; underlying pathology of familial dysautonomia; and, taste receptor formation. This knowledge will contribute to understanding normal and abnormal craniofacial development.